The use of paramagnetic particles (PMP) and their detection in a magnetic assay reader (MAR) represent a new "platform" technology that is adaptable to lateral flow membrane systems. In preliminary studies, the new technology is capable of delivering 3 to 4 logs increased sensitivity over existing lateral flow technologies that use immunogold or enzyme-tagged antibodies. We propose to develop a new rapid lateral flow system for Clostridium difficile toxins A and B using this technology. C. difficile is an excellent candidate to evaluate the technology. This anaerobic pathogen is the leading cause of nosocomial diarrhea and colitis in industrialized countries. Although the current antibody-based tests for C. difficile are more rapid than the tissue culture assay, which is considered the gold standard, they do not offer the same level of sensitivity. In Phase I, we will optimize the conditions needed to develop a PMP test for the toxins of C. difficile. We will optimize the PMP conjugation process, test formatting with separation membrane and capture line processes, evaluate stability, and develop a fecal sample diluent. A prototype device will be developed and we will initiate studies to evaluate performance characteristics. In addition, we will develop antibodies for the detection of iota toxin, a newly recognized C. difficile toxin. Phase II will be a natural extension of Phase I. The technology for producing the device will be transferred to a GMP facility, and we will evaluate GMP produced devices through in-house and on-site studies. Data will be collected and compiled, and 510(k) documents will be prepared. Using the PMP lateral flow technology platform that we will evaluate in Phase I, we will also develop a diagnostic C. difficile panel test, which will be useful for epidemiological and surveillance studies of C. difficile disease. In addition, we will develop a clinical diagnostic panel test for antibiotic associated diarrhea (AAD), including a PMP-based test for C. perfringens enterotoxin, another cause of AAD. The technology developed in this project will be widely applicable for the development of new highly sensitive stool antigen tests.